ELISHA MITCHELL SCIENTIFIC SOCIETY. 97 



muscular bulb, the middle part of the oesophagus. From this 

 point the lumen of the aliiuentary canal can be seen extending 

 down through the middle of the body, in which is a matrix that 

 develops many fat globules; the anus is situated at the beginning 

 of the hyaline portion of the tail end. The larva now leaves 

 the cyst cavity and enters a fresh root or different place in the 

 same root. It wanders for a time when it comes to rest, moults 

 a second time and then being fixed enlarges, or " swells up," 

 into a cyst with a flask-like body, the head projecting at one 

 end and the slender pointed tail at the other. At this time 

 prominent sexual transformations take place. Male — The male 

 moults again (third time), leaving the outer wall of the cyst 

 intact, while the body of the male elongates, narrows and becomes 

 coiled three or four times within the cyst. While this change is 

 going on the male moults again (fourth time). It is now from 

 1 mm. to 1.5 mm. long, anguillula-like, blunt at each end, 

 slightly curved at the caudal end, where are two curved spicules. 

 In the middle line of the body runs the alimentary canal, in the 

 posterior half of the body are the paired testes, which are united 

 into a common duct near the caudal end, and at the cloaca this 

 unites with the intestine. On each side within the body is a 

 muscular cord extending the entire length of the worm. Fe- 

 male — The female does not moult again, but continues to enlarge 

 enormously until it is gourd-shaped, and the paired generative 

 organs, opening by a common passage at the vulva in the pos- 

 terior part of the body, form long tubes which lie coiled in the 

 body of the cyst, free at their anterior end. As the embryos are 

 developing the body of the cyst breaks up into an amorphic 

 gelatinous mass in which the young larvae and eggs are found 

 floating within the eyst cavity. Length of life cycle, one month. 

 Metamorphism of Heterodera. — One of the features of 

 the greatest morphological interest in Heterodera is its singular 

 metamorphic character. This metamorphism finds its completest 

 analogy in some forms of the Coocidce^ where the larvae, after 



*StrabeIl, Ad. Uatersachuogeii uber dea Bau und die Entwickelung des Rubennema- 

 toden, Heterodera Schaehtii Schmidt. (Bibliotheca Zooiogica. Originalabhaudlungen 



